Sometimes a blade of a wind turbine is equipped with a winglet to improve the aerodynamic characteristics of the blade.
The winglet may be connected to the blade asides the final site of the wind turbine to simplify the transportation of the blade.
It is also possible to retrofit an already mounted blade with a winglet if there is the need due to specific conditions at the wind turbine site.
The mounting of blades towards a hub of a wind turbine has to be done very carefully due to the weight and due to the dimensions of the blade. This work becomes more difficult if the blade shows an additional winglet on its end.
This kind of work is quite expensive as special designed vessels with huge cranes are needed. Additionally there is the need for calm weather conditions to mount the huge blade to the hub.
It is known that lightning preferably strikes the wind turbine blades. Even the winglet may be harmed by lightning strikes.
Lightning strikes are especially problematic if the winglet contains a water-absorbing-material. The lightning strike evaporates the absorbed water into steam in only a split-second. Thus the winglet seems to explode due to the evaporated water.